Obama and Clinton visit John F Kennedy's grave

President Barack Obama has laid a wreath at the grave of John F Kennedy as part of a day of events honouring the assassinated president.

Mr Obama was joined at Arlington National Cemetery by former President Bill Clinton.

The 50th anniversary of Kennedy's assassination is on Friday.

Earlier, Mr Obama awarded the Presidential Medal of Freedom, the highest US civilian honour, to Mr Clinton and other prominent Americans.

Among this year's recipients were entertainer Oprah Winfrey, late astronaut Sally Ride and feminist Gloria Steinem.

Kennedy established a modern version of the awards but did not live to present the first medals.

'True champions'

Members of Kennedy's family stood by Mr Obama, Mr Clinton and former Secretary of State Hillary Clinton as a trumpet player performed Taps, the traditional US military mourning song, at the Kennedy grave.

Mr Obama made no public comments.

"Today, we salute fierce competitors who became true champions," the US president said earlier at the White House, speaking about each recipient of the medal before their official commendations.

He thanked Mr Clinton for "the advice and counsel that you've offered me, on and off the golf course. And most importantly, for your lifesaving work around the world, which represents what's the very best in America."

A recent political book reported that Mr Obama had gone to play a game of golf with Mr Clinton during the 2012 election campaign, but left the course early, supposedly saying he could only tolerate his fellow Democrat "in doses".

At Wednesday's ceremony, Mr Obama said Sally Ride - who became the first American woman in space in 1983 and died last year of pancreatic cancer - had served as a role model for his own children.

"Today our daughters, including Malia and Sasha, can set their sights a little bit higher because Sally Ride showed them the way," Mr Obama said.

The medals for Ride as well as civil rights activist Bayard Rustin and Senator Daniel Inouye, the first Japanese-American to serve in Congress, were awarded posthumously.

The other Medal of Freedom honourees were

Ernie Banks, all-star baseball player, elected to the Baseball Hall of Fame in 1977

Ben Bradlee, the Washington Post executive editor who oversaw its coverage of the Watergate scandal

Daniel Kahneman, a psychologist who won the Nobel Prize in Economics

Richard Lugar, former Senator of Indiana

Loretta Lynn, country music singer

Mario Molina, a chemist who researched how chlorofluorocarbon affected the environment

Arturo Sandoval, jazz trumpeter and winner of nine Grammys, who defected from Cuba